New .travis.yml for travis CI

Add requirements files to ease pip installation.
Added proxy support to Interface class. Included socks.py to remove need to install socks egg.
rm simplejson requirement
Refactored Interface class based on feedback from Yaro. Removed socks.py and replaced with test for socks load. Added docs about installing SocksiPy-branch.
fixed super call in Resource.datatype()
project.parent() returns None instead of throwing KeyError
Merge pull request #35 from pyxnat/travis

New .travis.yml for travis CI
Merge pull request #36 from rherrick/master

Add proxy support to Interface class
Merge pull request #37 from karchie/devel

fixed super call in Resource.datatype()
BF: python < 2.7 compatibility -- use explicit set([...])
Merge pull request #38 from neurodebian/master

BF: python < 2.7 compatibility -- use explicit set([...])
update for py3k

Fixed the following syntax issues across repo:
- print statement -> print function
- import StringIO -> import io.StringIO
- StandardError -> Exception
- exception <Exception> as ...
- urlparse -> urllib.parse.urlparse
- httplib.HTTPConnection -> http.client.HTTPConnection
Merge pull request #39 from pyxnat/py3kfix

update for py3k